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If your Windows PC is booting in EFI mode, Microsoft has blocked the loading of legacy or non-Windows operating systems from the BCD menu.
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It is not fundamentally incompatible with dual-booting, but the way that Microsoft and PC manufacturers have implemented UEFI, it makes it a lot harder to do so. Newer computers are shipping with a BIOS replacement called UEFI – short for Unified Extensible Firmware Interface – that completely changes the way operating systems interact with and are loaded from the hardware in your PC. The changes are not small and have had a massive effect on the process of dual-booting on a Windows machine. With the release of Windows 8 and Windows 10, many new computers are shipping with something known as the UEFI firmware and boot manager in place of the traditional BIOS and MBR approach to starting up your PC.
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